Why do you think that? Turning off DRM would be trivial and they might even end up being legally obligated to do just that either because of laws or because of how whatever hypothetical bankruptcy they go through might be structured. Never mind Valve going belly up seems highly unlikely to begin with. If it does ever happen and it happens in the way you describe, piracy will absolutely skyrocket and people will stop buying games online after they’ve had their trust shaken.